11-keto-tigogenin



2,854,451 Patented Sept. 30, 1958 ll-KETO-TIGOGENIN Earl M. Chamberlin,Westfield, and John M. Chemerda,

Metu'chen, N. J., assignors to Merck & Co., Inc., Rahway, N. J acorporation of New Jersey No Drawing. Original application March 10,1951, Serial No. 215,026. Divided and this application September 20,1951, Serial No. 247,563

3 Claims. (Cl. 260239.55)

This application is a divisional of copending application Serial No.215,026, filed March 10, 1951 and now abandoned.

This invention is concerned with novel chemical compounds of thecyclopentanopolyhydrophenanthrene series and processes for preparing thesame; more particularly, it relates to novelcyclopentanopolyhydrophenanthrene compounds having functionalsubstituents in ring C; and specifically it relates to new compoundshaving a hydroxyl or keto substituent at the 11 position, and toprocesses for the preparation of such compounds.

Compounds of the adrenal cortex, such as Kendalls compound E(cortisone), have been found to be of great value in the treatment ofvarious diseases. Further, it is likely that Kendalls compound E and/ orother closely related ll-hydroxy steroids will find increasingtherapeutic use in the future. Unfortunately, the only method for thepreparation of such compounds presently available utilizes desoxycholicor cholic acids as the starting material. Cholic and desoxycholic acidshave hydroxy substituents in ring C at the 12-position, thus providing ameans for introducing a functional substituent at the 11 position.However cholic and desoxycholic acids, which are obtained from animalbile, are only available in limited amounts. Heretofore no practicalmethod was available whereby a functional group could be introduced inring C which would permit the use of more abundant steroids such as thesterols, ergosterol, cholesterol, stigmasterol, or plant sapogenins,such as diosgenin, tigogenin, and the like.

It is an object of the present invention to provide a process forintroducing a functional group in ring C at the 11 position. It is afurther object to provide a process for convertingcyclopentanopolyhydrophenanthrene compounds having a double bond in the7:8 position to the corresponding cyclopentanopolyhydrophenanthrenecompound having a hydroxyl or keto group at positions 7 and 11. Anotherobject is to provide new compounds of the steroid series havingfunctional groups in ring C suitable for the preparation of othercy-clopentanopolyhydrophenanthrene compounds. Other objects will beapparent from the detailed description hereinafter provided.

In accordance with our invention, we have now found that compounds ofthe cyclopentanopolyhydrophenanthrene series having an ll-ketosubstituent can be synthesized by reactions indicated as follows:

l od

IIIA

VII

These reactions are carried out as follows:

A cyclopentanopolyhydrophenanthrene compound having a 7:8 double bond(1) is reacted with mercuric acetate producing the correspondingcompound having conjugated double bonds in the 7:8 and 9:11 positions(II) which is treated with a per acid, thus forming an epoxiderepresented by the alternate Formulas IIIA and IIIB. (At present theexact structure of the expoxide is not known and it is represented bythe alternative forms IIIA and IIIB. Alternatively it is possible thatthe product obtained is a mixture of these two forms.) This epoxide isthen treated with an adsorbent to form the corresponding A -dihydroxycompound IV.

The A -dihydroXy compound IV is reacted with an oxidizing agent toconvert the hydroxy substituents to keto groups, thus obtaining thecorresponding A -diketo cyclopentanopolyhydrophenanthrene derivatives V.These diketo compounds are then reduced to saturate the A double bondand form the corresponding 7,11-diketo compound VI. The saturated diketocompound is then reduced to eliminate the 7-keto substituent, thusproducing the corresponding ll-keto compound VII. The latter compoundsare useful intermediates for the preparation of ll-keto compounds havingdesirable therapeutic properties.

The A -compounds of the cyclopentanopolyhydrophenanthrene series areconveniently prepared by reacting the corresponding A' compound withmercuric acetate. We have found that this reaction is preferablyeffected by reacting the A' -compound with mercuric acetate and glacialacetic acid in the presence of a suitable solvent medium such aschloroform. The reaction is conveniently conducted by stirring thereaction mixture for l624 hours. After the reaction is completed, the ncompound is recovered from the reaction mixture by removing theprecipitated mercurous acetate, and concentrating the solution underdiminished pressure. if desired, the residue may be further purified bycrystallization from suitable solvents. Thus, this process can beutilized to prepare A -pregnadiene-3-ol-20-0ne-3- acetate, and A-dehydrotigogenin acetate from A pregnenolone acetate andM-dehydrotigogenin acetate respectively. Alternatively, other acylderivatives of these starting materials or the 3-hydroxy compounds maybe utilized as starting materials in our process to prepare thecorresponding A -compounds.

Further, the 3-hydroxy-A -choladienic acid, which is also useful as astarting material in the processes of our invention, is readily obtainedby reducing 3-hydroxy- 1Z-keto-A -choladienic acid. This is convenientlyaccomplished by reacting the keto acid with hydrazine hydrate and analkali metal hydroxide in the presence of a suitable high boilingsolvent such as diethylene glycol.

This invention is concerned with compounds of the type represented byintermediate VII above, and with processes of producing the same.Compound V11 may be represented by the following formula:

The starting materials used in the process of this invention, namely,the 7,11-diket0 compounds shown by Formula VI, may be obtained asdescribed in copending application, Serial No. 215,026, filed March 10,1951.

Pursuant to our invention, we have fou d that the 7,11-diketocyclopentanopolyhydrophenanthrene compounds can be reduced to thecorresponding ll-keto compounds. We prefer to effect this reduction byreacting the 7,11-diketo compound with hydrazine hydrate and an alkalimetal hydroxide at elevated temperatures in a high boiling solventmedium, for example, diethylene glycol. it is surprising that underthese reaction conditions the ll-keto group is not simultaneouslyreduced along with the 7-keto group. On the contrary, we have found thatunder optimum conditions excellent yields of the desired ll-ketocompounds are obtained by this reduction process.

Thus, in accordance with the processes described above 3-hydroxy-11-keto-A -ergostene, 3-hydroxy-11-keto-bisnorallocholanic acid,3-hydroxy-1l-ketotigogenin, and the corresponding esters, acylderivatives, or esterified acyl derivatives can be prepared from thecorresponding 7,11-diketo compounds. If desired, these 3-hydroxy-11-keto compounds may be oxidized to obtain 3,11-

EXAMPLE 1 Preparation of 3-ltydroxy-l I -ket0-A -crg0sleizc from 3-rzcet0xy-7,I I -di/cet0-A -crg0stene A mixture of 1 g. of3-acetoxy-7,ll-diketo-n ergostene, 5 cc. of diethylene glycol, 0.455 g.powdered potassium hydroxide and 0.5 cc. of hydrazine hydrate was heatedat a temperature of 132 C for 1 hour. The temperature was then raised to190-200 C. and the reaction mixture was held at this temperature for 2hours. Water was allowed to distill off during this heating period.

Fifteen cubic centimeters of water were added to the cooled reactionmixture and then the dark brown suspension was acidified withhydrochloric acid and filtered. The brown product was dissolved in hotacetone, filtered and then treated with charcoal (Darco) and filtered.The solvent was evaporated in a stream of nitrogen and the residuedissolved in 25 cc. of benzene and chromatographed on 20 g. of acidwashed alumina.

Thee column was developed with the following solvents:

Benzene Ether Methanol Ethyl acetate Chloroform Acetone The benzenefractions yield a brown amorphous solid. All other fractions were emptyor gave brown tars.

The brown amorphous material was dissolved in 30 cc. of benzene and 10cc. of petroleum ether added and the solution chromatographed on 20 g.of acid washed alumina. The chromatograph was developed with thefollowing solvents:

Petroleum ether/benzene 1:3 Benzene Ether Methanol From the etherfractions 150 mg. of crystalline 3-hydroxy-ll-keto-A -ergostene wasobtained which on recrystallization from methanol melted at 173174 C.[a] =+26.6, a=0.485, C=0.91% CHCI Analysis.Calc. for C H O C, 81.10; H,11.17. Found: C, 81.72; H, 11.29.

3.175 grams of 3-hydroxy-11-keto-A -ergostene was refluxed with 20 cc.of acetic anhydride for 1 hour. On cooling to room temperature the3-acetoxy compound crystallized out. It was filtered and washed with alittle cold methanol. Yield: 2.685 g., M. P. 122124 C. A small sample of3-acetoxy-11-keto-A -ergostene recrystallized from methanol melted at129.5131.5 C.

Analysis.Calc. for C H O C, 78.90; H, 10.59. Found: C, 78.95; H, 10.82.

EXAMPLE 2 Degradation of 3-acet0xy-11-ket0-A -erg0stene t0 methyl3-acet0xy-11-ket0bislzorallocholalzate 2.36 grams of 3-acetoxy-ll-keto-A-ergostene was dissolved in 75 cc. of chloroform and treated with ozoneat 0 C. The reaction mixture was diluted with cc. of glacial acetic acidand oxidized at room temperature with 1 g. of chromic acid dissolved in1 cc. of water and 50 cc. of glacial acetic acid. Five cubic centimetersof 5 methanol were added to destroy excess chromic acid and the solventwas removed in vacuo to almost dryness.

The residue in the flask was dissolved by shaking twice with a mixtureof 100 cc. of benzene and 50 cc. of 5% sulfuric acid. The combinedaqueous acid solution was extracted with an additional 50 cc. ofbenzene. The combined benzene extracts were washed with 50 cc. of waterand dried over anhydrous magnesium sulfate. The benzene was removed invacuo and the residue dissolved in 250 cc. of ether.

The ethereal solution was stirred with 5 g. of anhydrous sodiumcarbonate and 10 cc. of water for 45 minutes. The ether layer wasremoved by decantation and the aqueous layer washed twice by decantationwith ether.

The aqueous layer was acidified with 50% sulfuric acid and the liberatedacid 3-acetoxy-1l-keto-bisnorallocholanic acid was extracted into etherand separated from the aqueous layer.

The ethereal solution of the acid was treated with an ethereal solutionof diazomethane and the ether evaporated to small volume on the steambath whereupon the methyl ester crystallized out. Yield, 750 mg.Recrystallized from methanol the substance, methyl 3-acetoxy-11-ketobisnorallocholanate, melted at 191-194 C.

Analysis.Calc. for C H O C, 71.73; H, 8.91. Found: C, 71.89; H, 9.15.

EXAMPLE 3 Preparation of methyl 3,11-diketbisnorallocholanate from3-acet0xy-1 1-ket0bisnorall0ch0lanate 750 mg. of methyl3-acetoxy-1l-ketobisnorallocholanate (prepared as shown in Example 2)was refluxed with 30 cc. of potassium hydroxide for one half hour. Fiftycubic centimeters of water were added, the precipitated product wasfiltered and washed with water. The product, methyl3-hydroxy-1l-ketobisnorallocholanate, melted at 176178.5 C.

The 3-hydroxy compound was dissolved in approximately 30 cc. of acetoneand oxidized at room temperature by addition of 200 mg. of chromiumtrioxide in 5 cc. of 1 N sulfuric acid. The oxidizing agent was addeddropwise with stirring over a period of one half hour. The reactionmixture was stirred an additional minutes, 1 cc. of methanol was addedand the precipitated chromium salts filtered 0E.

The acetone solution was diluted with approximately 100 cc. of waterwhich precipitated the product. After cooling, the product was filteredoff and washed with water. Recrystallized from acetone the substance,methyl 3,11diketobisnorallocholanate, melted at 201-204 C. Mixed meltingpoint with an authentic sample 201-204 C. Mixed melting point with thecisisomer 171-193 C. Yield 250 mg., 37% yield, [a] =+63.

Analysis-Cale for C H O C, 73.96; H, 8.90. Found: C, 74.18; H, 9.20.

EXAMPLE 4 Methyl 3-hydr0xy-11-ket0-bisn0rall0cholanate C O OH A00 I =0H0 III TV One gram of 3-acetoxy-7,11-diketo-A -ergostene (I) obtained asdescribed in copending application Serial No.

215,026, filed March 10, 1951, was dissolved in cc. of chloroform andozone was passed through at ice bath temperature until the approximatetheoretical amount of ozone was absorbed. The reaction mixture wasdiluted with 100 cc. of glacial acetic acid, cooled to 5 C. and oxidizedwith 0.5 g. chromic acid dissolved in 0.75 cc. water and 50 cc. glacialacetic acid.

After standing overnight, 5 cc. of methanol was added and the solventwas removed in vacuo to practically dryness. The residue in the flaskwas dissolved by shaking twice with a mixture of 25 cc. of 5% sulfuricacid and 50 cc. of benzene. The combined benzene solutions were driedover anhydrous magnesium sulfate, and the benzene was evaporated on thesteam bath in a stream of nitrogen.

The residue was dissolved in 200 cc. of ether and stirred with 5 g. ofsodium carbonate and 2 cc. of water for 21 hours. The sodium salt of3-acetoxy-7,l1-diketobisnorallocholanic acid (II) was filtered off anddried in a vacuum desiccator.

The dried sodium salt was suspended in 25 cc. of ether and 25 cc. of 50%sulfuric acid was added in small portions until the mixture wasdefinitely acid. 100 cc. of ether was added to bring about completesolution of all solids. The aqueous layer was separated and extractedonce with 50 cc. of ether.

The combined ethereal solutions were dried over anhydrous magnesiumsulfate and then evaporated on the steam bath to a small volume,whereupon 3-acetoxy-7,11-

" diketo-bisnorallocholanic acid (H) crystallized out. The

product was recrystallized from ether; M. P. 235238 C. [0c] =24.6,oc=0.68, C=1.38% CHCl Analysis.Calcd. for C H O C, 68.87; H, 8.19.Found: C, 68.67; H, 8.04.

mg. of 3-acetoxy-7,ll-diketo-bisnorallocholanic acid was suspended in 25cc. of ether and esterified with diazornethane. All solid dissolved andon evaporation of the ether to a small volume, the methyl ester (III)crystallized. M. P. 226.5229 C. Mixed melting point with an authenticsample of the ester: 227230 C.

5 g. of methyl 3-acetoxy-7,ll-diketo-bisnorallocholanate (III) and 2.07g. of powdered potassium hydroxide were placed in a 50 cc. round-bottomflask. 25 cc. of diethylene glycol and 2.3 cc. of 85% hydrazine hydratewere added and the temperature raised to l40 C. and held for 1 hour. Thetemperature was then raised to 200 C. and held for 2 hours.

After cooling, the reaction mixture was dissolved in benzene and water,50% sulfuric acid added until an acid reaction was obtained. The benzenelayer was separated, and the aqueous layer extracted three times with 50cc. of benzene. The combined benzene solutions were washed with waterand dried over anhydrous magnesium sulfate.

The benzene was treated with Darco. The benzene solution wasconcentrated in vacuo to dryness, the residue was dissolved in ether andesterified with an ethereal solution of diazomethane. The ether wasevaporated, and the methyl 3-hydroxy-1l-keto bisnorallocholanate (IV)was recrystallized from methanol, M. P. 1775-1805.

7 Mixed M. P. with an authentic sample, 177179 C. ta1 =+4L EXAMPLE 5Preparation of 3-lzydr0xy-Z1-ket0bisnorallocholanic acid and its methylester from 3-acet0xy-7,1Z-diketobisnorallocholmzic acid Two grams of3-acetoxy-7,11-diketobisnorallocholanic acid (prepared as described inExample 4) were stirred in a 50 cc. round bottom flask with cc. ofdiethylene glycol, 1.5 g. of powdered potassium hydroxide and 1.5 cc. of85% hydrazine hydrate and the temperature raised slowly to 135140 C. andheld for 45 minutes. The temperature was then raised to 190-195 C. andheld for one hour.

After cooling the reaction mixture was acidified with 2 N sulfuric acid,diluted with 30 cc. of distilled water and filtered. The tan, dried cakeweighed 1.57 g. The product was dissolved in benzene-ethanol, treatedwith Darco, filtered through Supercel and the filtrate was concentrateduntil crystallization started. Recrystallization from benzene gave 0.60g. of product melting at 258 to 2614 C.

Anaiysis.-Calc. for C I-1 0 C, 72.89; H, 9. Found: C, 72.82; H, 9.34.

An additional 0.60 g. of lower melting acid (M. P. 252258) was recoveredfrom the mother liquors of the above product.

A sample of the acid was esterified with diazomethane in etherealsolution to give methyl 3-hydroxy-1l-ketobisnorallocholanate (III)melting point 175177.5, lal +423. The melting point of a mixture of thiscompound with an authentic sample was 175-178".

EXAMPLE 6 Preparation 0f 11 -ket0tig0genin from 3-acet0xy-7,11-diketotigogenin A mixture of 0.42 g. of 3-acetoxy-7,1l-diketotigogenin,2.1 ml. of diethylene glycol, 0.20 g. of powdered potassium hydroxide,and 0.21 ml. of hydrazine hydrate (85%) was stirred while being heatedin an oil bath. The temperature was raised to 12030 C. and held therefor fifteen minutes. The temperature was then raised to 195-200 C. forminutes. After cooling, the mixture was poured into 25 ml. of ice watermixture and the resulting mixture was neutralized with dilute sulfuricacid. The solid product was removed by filtration and was washed wellwith water. The dried crude product Was dissolved in 20 ml. of methanol,and boiled for five minutes with a small amount of activated charcoal.After removing the charcoal by filtration, the methanol solution wasconcentrated to ten ml. Water was added to the hot solution untilcrystallization was incipient. Upon cooling, 0.22 g. of ll-ketotigogeninin the form of needles were obtained, M. P. 220226 C. Recrystallizedfrom a mixture of ethyl acetate-petroleum ether, the product melted atZZZ-226 C.

Analysis.-Calcd. for C H O C, 75.31; H, 9.83. Found: C, 75.40; H, 10.20.

ll-ketotigogenin acetate was made by refluxing 11- ketotigogenin withacetic anhydride. Recrystallized from methanol, it melted at 224229 C.

Various changes and modifications may be made in carrying out thepresent invention without departing from the spirit and scope thereof.Insofar as these changes and modifications are within the purview of theannexed claims, they are to be considered as part of our invention.

We claim:

1. ll-ketotigogenin.

2. S-acetoxy-ll-ketotigogenin.

3. A compound from the group consisting of ll-ketotigogenin and3-acyloxy-1l-ketotigogenin wherein the acyl substituent is a lower fattyacid radical.

References Cited in the file of this patent UNITED STATES PATENTS2,403,683 Reichstein July 9, 1946 2,447,325 Gallagher Aug. 17, 19482,471,697 Minlon May 31, 1949 OTHER REFERENCES Wettstein et al.: Helv.Chim. Acta, vol. 30, pp. 12625 (1947).

Fieser et 211.: Natural Products Related to Phenanthrene, 3rd ed., pp.409410, 425 (1949).

3. A COMPOUND FROM THE GROUP CONSISTING OF 11-KETOTIGOGENIN AND3-ACYLOXY-11-KETOTIGOGENIN WHEREIN THE ACYL SUBSTITUENT IS A LOWER FATTYACID RADICAL.